Patterning materials is an integral part of integrated-circuit (IC) processing. The patterning process may include a variety of processing techniques, including, for example, photo-lithographic processing, etching of metal stacks, resist stripping, etc. Such patterning processes are used in the production of various devices, such as, for example, memory devices. Examples of memory devices include dynamic random access memory (DRAM) devices and magnetoresistive random access memory (MRAM) devices.
Many patterning steps result in the generation of processing byproducts that must be removed to maintain device integrity. For example, reactive ion etching (RIE) can cause residue contamination where byproducts remain on the surfaces of the structure being processed. For example, byproducts or residue may include halogen-based residues (e.g., fluorocarbon byproducts when a CHF3 etchant is used), metal halides (e.g., when a chlorine containing etchant is used to pattern metal stacks), organosilicates (e.g., when silicon is present during an etching process), etc. Contamination during production can lead to, besides other things, bond disruption of subsequently applied layers, and increased resistance, both of which can affect reliability of the device being processed. As such, byproducts of patterning process steps need to be removed.
Structures resulting from patterning processes can include a variety of patterned metal containing surfaces. These metal-containing surfaces can include, for example, in the case of forming MRAM devices, metals such as nickel, cobalt, iron and alloys thereof. During processing, these metal-containing surfaces can be exposed to etch byproducts. Various aqueous compositions are capable of removing the byproducts, such as, organosilicates, metal halides, and other compounds formed after patterning of such structures. For example, such aqueous compositions may include HF, HCl, HNO3, among other components. However, using aqueous based compositions in removing these etch byproducts can lead to oxidation/corrosion of the metal-containing surfaces (e.g., nickel, iron, etc.). In other words, the water present in these compositions can lead to undesirable oxidation of the metal surfaces. In addition, the presence of water can allow for the formation of reactive chemical species that can have corrosive effects on the structure. Thus, cleaning etch byproducts with aqueous based compositions is typically undesirable.